Certain types of measuring and testing involve mounting the product to be tested upon a platform or table capable of limited movement in one or more axes of motion. The table is shaken or vibrated using a fluid vibrator, usually pneumatic as opposed to hydraulic, coupled to the table. An example of such an arrangement is disclosed in U.S. Pat. No. 5,365,788 (Hobbs) and involves a table vibrated by what the patent calls exciters.
Vibrators (or exciters) are available in a variety of configurations. Manufacturers of pneumatic vibrators include Cleveland Vibrator Co., Cleveland, Ohio, and Martin Engineering Co., Neponset, Ill. The Model VMS vibrator made by Cleveland Vibrator Co. includes a chrome-plated piston movable in a housing. At one end, the housing is closed by a bolted cap and the other end of the housing is open. The piston impacts directly against a channel mounting plate provided by the vibrator purchaser.
The PV Series piston vibrators made by Martin Engineering Co. include a chromed piston mounted for movement within an optional hollow cylindrical liner, the latter being stationary in the housing. The liner permits operating the vibrator without lubrication. The liner and piston are in a housing closed at one end by a bolted, flange-mounted cap and at the other end by a replaceable strike plate fitted into the housing. It is understood that the strike plate is against some sort of customer-supplied channel mounting plate.
While these prior art vibrators are understood to have been generally satisfactory for their intended purposes, they are not without disadvantages. One involves seeming lack of flexibility in mounting and use. As it is understood, the Cleveland and Martin vibrators are to be mounted directly against a mounting plate. Special arrangements are apparently needed if something is needed other than orthogonal mounting or mounting using a plate against the vibrator.
Another seeming disadvantage of prior art vibrators is that they require a good deal of machining over the course of manufacture. Of course, this adds incrementally to cost and, therefore, to selling price.
Yet another seeming disadvantage is that the designers of such vibrators have not fully appreciated how to make the vibrator more easily serviceable. Nor, seemingly, is there a full appreciation of how to enhance cooling of certain vibrator parts. (The latter is relevant because in operation, pneumatic vibrators become very hot.)
An improved pneumatic vibrator which addresses disadvantages of prior art vibrators would be an important advance in this field of technology.